I’d advocate decoupling your long polling endpoints entirely from the rest of your web app stack. Personally I like Node.js for this, but Tornado would work just fine too (I’ve experimented successfully with Tornado long polling in the past).

Self promoting here (not sure if that’s OK by Quora community standards or not), but the site we just launched, Lanyrd.com, answers this question. It lets you sign in with Twitter and see what events your Twitter friends are tracking, attending or speaking at. It also lets you create a conference profile page—here’s mine, which shows the upcoming conferences I am tracking at the moment: http://lanyrd.com/people/simonw/

I think that “bad technology” can kill a startup, but slightly different variations of good technology don’t have much effect. Choose what you know/like best. And Ruby and Python are both in this latter category.